Checking membership (in, not in) in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the in keyword check in a pytest assertion?

The in keyword checks if a value or element exists inside a container like a list, string, or dictionary keys.

beginner

How do you assert that an item is NOT in a list using pytest?

Use assert item not in list to check the item is absent from the list.

beginner

Example: <br> assert 'apple' in fruits <br> What happens if 'apple' is not in fruits?

The test will fail and pytest will show an AssertionError because the condition is false.

intermediate

Why is checking membership useful in software testing?

It helps verify if expected data or elements appear in outputs, lists, or responses, ensuring correct program behavior.

beginner

What types of containers can you check membership in with in and not in?

You can check membership in lists, tuples, sets, strings, and dictionary keys.

What does assert 'cat' in animals check?

A 'cat' is a variable

B 'cat' is not in animals

C animals is empty

D 'cat' is an element in the animals container

The assertion checks if 'cat' exists inside the animals container.

How do you assert that 'dog' is NOT in the list pets?

A assert 'dog' in pets

B assert 'dog' not in pets

C assert pets not in 'dog'

D assert not pets in 'dog'

Use 'assert 'dog' not in pets' to check absence.

Which container membership does in NOT check?

A Integer

B String

C List

D Dictionary keys

Membership checks require containers; integers are not containers.

If assert 'x' in 'xyz' fails, what does it mean?

A 'x' is in 'xyz'

B Syntax error

C 'x' is not in 'xyz'

D Test passed

If the assertion fails, 'x' is not found in 'xyz'.

What error does pytest show if a membership assertion fails?

A AssertionError

B TypeError

C ValueError

D IndexError

Failed assertions raise AssertionError in pytest.

Explain how to use in and not in in pytest assertions with examples.

Think about checking if an item exists or does not exist in a list or string.

Why is checking membership important in software testing? Give a simple scenario.

Consider how you confirm something is included or excluded in a result.